Drug delivery device with pneumatic power pack

ABSTRACT

A drug delivery device configured to provide a dose of medicament is disclosed. The drug delivery device includes a main housing, a syringe arranged in the main housing, and a pneumatic power pack arranged in the main housing. The pneumatic power pack includes a pressurized gas source storing pressurized gas, a valve for the pressurized gas source, a sleeve having an inner wall, and a plunger. The sleeve is configured to receive pressurized gas released from the pressurized gas source. The plunger is in sliding gas-tight engagement with the inner wall of the sleeve. Upon activation of the valve, the valve releases the pressurized gas, and the released pressurized gas flows into the sleeve and propels the plunger in a distal direction with respect to the sleeve and the syringe, so as to eject medicament from the syringe.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is an application for reissue of U.S. Pat. No. 10,328,205, whichissued on Jun. 25, 2019.

FIELD OF THE PRESENT PATENT APPLICATION

This present disclosure relates to relates to drug delivery devices suchas automatic injection devices.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

In some situations, it is desirable for patients to be able toadminister drugs and medicament by themselves, e.g., without the needfor trained medical staff to administer the drugs. There are a number ofdifferent existing delivery devices with varying degrees of automaticfunctions. For instance, existing automatic injection devices provide ameans for automatically propelling a plunger forward to eject medicamentfrom the automatic injection device in response to activation of thedevice.

In existing devices, the means for automatically propelling the plungerforward to eject the medicament are often complex and expensive tomanufacture. There is, therefore, a desire to reduce the cost ofmanufacturing automatic injection devices while maintaining thereliability of the injection device to eject the dose of medicament.

Further, for some types of medicaments, there is a desire to eject themedicament at a substantially constant force. However, certain existingdevices for ejecting the medicament at a substantially constant forceare complex and expensive to manufacture. There is a desire to reducethe cost of manufacturing automatic injection devices while maintainingthe reliability of the injection device to eject the medicament at asubstantially constant force.

SUMMARY

A drug delivery device configured to administer a dose of medicament isprovided. In an example embodiment, the drug delivery device includes amain housing, a syringe arranged in the main housing, and a pneumaticpower pack arranged in the main housing. The syringe holds a medicament.The pneumatic power pack includes: (i) a pressurized gas source storingpressurized gas; (ii) a valve for the pressurized gas source; (iii) asleeve having an inner wall, wherein the sleeve is configured to receivepressurized gas released from the pressurized gas source; and (iv) aplunger axially movable with respect to both the sleeve and the syringe.The plunger is in sliding gas-tight engagement with the inner wall ofthe sleeve. Upon activation of the valve, the valve releases thepressurized gas, and the released pressurized gas flows into the sleeveand propels the plunger in a distal direction with respect to the sleeveand the syringe, so as to eject the medicament from the syringe.

In another example embodiment, the drug delivery device includes a mainhousing, a medicament container arranged in the main housing, a needlecover axially movable with respect to the main housing, and a pneumaticpower pack arranged in the main housing. The medicament container holdsa medicament. The pneumatic power pack includes: (i) a pressurized gassource having a valve and storing pressurized gas; (ii) a sleeve havingan inner wall, wherein the sleeve is axially moveable with respect tothe main housing; and (iii) a plunger comprising an inner chamber. Theplunger is axially movable with respect to both the sleeve and themedicament container. Further, the plunger is in sliding gas-tightengagement with the inner wall of the sleeve. Still further, the sleeveand the inner chamber are configured to receive pressurized gas releasedfrom the pressurized gas source. Axial movement of the needle cover in aproximal direction causes axial movement of the sleeve in the proximaldirection, and the axial movement of the sleeve in the proximaldirection activates the valve to release the pressurized gas. Thereleased pressurized gas flows into both the sleeve and the innerchamber and propels the plunger in a distal direction with respect tothe sleeve and the medicament container, so as to eject the medicamentfrom the medicament container.

In still yet another example embodiment, the drug delivery deviceincludes a main housing, a medicament container arranged in the mainhousing, and a pneumatic power pack arranged in the main housing. Themedicament container holds a medicament. The pneumatic power packincludes: (i) a pressurized gas source storing pressurized gas; (ii) avalve for the pressurized gas source; (iii) a sleeve having an innerwall; and (iv) a plunger comprising an inner chamber and a pressurerelease valve configured to release pressure from the inner chamber whenthe pressure in the inner chamber reaches a threshold pressure level.The plunger is axially movable with respect to both the sleeve and themedicament container. Further, the plunger is in sliding gas-tightengagement with the inner wall of the sleeve. The sleeve and the innerchamber are configured to receive pressurized gas released from thepressurized gas source. The valve for the pressurized gas source isconfigured to release the pressurized gas upon activation of the valve.Further, the released pressurized gas flows into both the sleeve andinner chamber and propels the plunger in a distal direction with respectto the sleeve and the medicament container at a substantially constantforce, so as to eject the medicament from the medicament container.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the figures and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments are described herein with reference to thedrawings, in which:

FIG. 1 illustrates a perspective view of an example drug delivery devicehaving an example pneumatic power pack, according to an exampleembodiment of the present disclosure.

FIG. 2 illustrates an exploded, perspective view of example componentsof the drug delivery device of FIG. 1 in an initial state prior toinjection, according to an example embodiment of the present disclosure.

FIG. 3 illustrates a front view of the example drug delivery device ofFIG. 1 during dose delivery, according to an example embodiment of thepresent disclosure.

FIG. 4 illustrates a perspective view of example components of the drugdelivery device of FIG. 1 during dose delivery, according to an exampleembodiment of the present disclosure.

FIG. 5 illustrates a perspective view of example components of the drugdelivery device of FIG. 1 at the end of dose delivery, according to anexample embodiment of the present disclosure.

FIG. 6 illustrates a perspective, cross-sectional view of an exampleplunger of the drug delivery device of FIG. 1 , according to an exampleembodiment of the present disclosure.

FIG. 7 illustrates a perspective view of an example drug delivery devicehaving an example pneumatic power pack, according to an exampleembodiment of the present disclosure.

FIG. 8 illustrates a perspective, cross-sectional view of the pneumaticpower pack of the drug delivery device of FIG. 7 , according to anexample embodiment of the present disclosure.

FIG. 9 illustrates a perspective view of an example valve of thepneumatic power pack of FIG. 8 , according to an example embodiment ofthe present disclosure.

FIG. 10 illustrates a perspective, cross-sectional view of the pneumaticpower pack of the drug delivery device of FIG. 7 during dose delivery,according to an example embodiment of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented herein. It will be readily understood that the aspects of thepresent disclosure, as generally described herein, and illustrated inthe figures, can be arranged, substituted, combined, separated, anddesigned in a wide variety of different configurations, all of which areexplicitly contemplated herein.

The methods and systems in accordance with the present disclosurebeneficially provide improved methods and systems for propelling aplunger forward so as to eject the medicament from an automaticinjection device. The disclosed methods and systems provide a reliable,intuitive, and user-friendly drug delivery device that uses apressurized gas to eject a dose of medicament. Further, the disclosedmethods and systems provide a cost effective means for propelling theplunger forward so as to eject the medicament and thus help to reducethe cost of manufacturing automatic injection devices.

In accordance with an example embodiment of the present disclosure, adrug delivery device includes a main housing, a syringe arranged in themain housing, and a pneumatic power pack arranged in the main housing.The syringe holds a dose of medicament. The pneumatic power packincludes a pressurized gas source storing pressurized gas, a valve forthe pressurized gas source, a sleeve having an inner wall, and aplunger. The sleeve is in gas-tight engagement with the pressurized gassource and is configured to receive pressurized gas released from thepressurized gas source. The plunger is at least partly surrounded by thesleeve and is axially movable with respect to both the sleeve and thesyringe. Further, the plunger is in sliding gas-tight engagement withthe inner wall of the sleeve. Upon activation of the valve, the valvereleases the pressurized gas. The released pressurized gas then flowsinto the sleeve and propels the plunger in a distal direction withrespect to the sleeve and the syringe, so as to eject the medicamentfrom the syringe.

In an example embodiment, the plunger includes an inner chamber forreceiving the released pressurized gas. In this embodiment, uponactivation of the valve, the released pressurized gas flows into boththe sleeve and the inner chamber. This pressurized gas then propels theplunger in the distal direction with respect to the sleeve and thesyringe, so as to eject the medicament from the syringe.

FIG. 1 generally illustrates an example drug delivery device that usespressurized gas to deliver a dose of medicament. In particular, FIG. 1illustrates a drug delivery device 100 in an initial state prior toinjection. Further, FIG. 2 illustrates an exploded view of thecomponents of the drug delivery device 100 in the initial state prior toinjection.

As seen in FIGS. 1 and 2 , drug delivery device 100 includes a mainhousing 102 and a syringe 104 arranged in the main housing 102. Mainhousing 102 includes a first housing portion 106 and a second housingportion 108. First and second housing portions 106, 108 includecorresponding engagement features for providing an engagement betweenthe two housing portions 106, 108. In an example embodiment, duringassembly of the drug delivery device 100, the first and second housingportions are irreversibly attached to one another. Although main housing102 is depicted as comprising first and second housing portions 106,108, in other examples, main housing 102 may comprise more or fewerportions. For instance, in an example embodiment, the main housing 102is of unitary construction.

With reference to FIG. 2 , the syringe 104 includes a syringe body 110holding a medicament 112, a needle 114, and a needle cover 116 coveringthe needle 114. A piston or stopper 118 is disposed in the syringe body110. The drug delivery device 100 further includes a pneumatic powerpack 120 for ejecting the medicament from the syringe 104. The pneumaticpower pack 120 includes a pressurized gas source 122 storing pressurizedgas 123, a valve 124 for the pressurized gas source 122, a sleeve 126,and a plunger 128.

The sleeve 126 is in gas-tight engagement with the pressurized gassource 122 and is configured to receive pressurized gas 123 releasedfrom the pressurized gas source 122. As used herein, “gas-tightengagement” means an engagement providing a seal that prevents orsubstantially prevents leakage of gas through the seal during the dosedelivery process. By the term “substantially” it is meant that therecited characteristic, parameter, or value need not be achievedexactly, but that deviations or variations, including for example,tolerances, measurement error, measurement accuracy limitations andother factors known to skill in the art, may occur in amounts that donot preclude the effect the characteristic was intended to provide. Inan example embodiment, the gas-tight engagement prevents or limitsleakage of gas such that less than 0.5% of the released pressurized gas123 received in sleeve 126 is able to leak through the gas-tightengagement during the dose delivery process. In another exampleembodiment, the gas-tight engagement prevents or limits leakage of gassuch that less than 1% of the released pressurized gas 123 received insleeve 126 is able to leak through the gas-tight engagement during thedose delivery process. In yet another example, the gas-tight engagementprevents or limits leakage of gas such that less than 5% of the releasedpressurized gas 123 received in sleeve 126 is able to leak through thegas-tight engagement during the dose delivery process.

The sleeve 126 has an inner wall 130, and the plunger 128 is in slidinggas-tight engagement with the inner wall 130 of the sleeve 126. Duringan injection process of drug delivery device 100, the pressurized gas123 will axially move the plunger 128 with respect to the sleeve 126 andconsequently with respect to the syringe 104. In particular, uponactivation of valve 124, the valve 124 releases the pressurized gas 123.The pressurized gas 123 then flows into the sleeve 126 and propels theplunger 128 in distal direction 132 with respect to the sleeve 126 andsyringe 104, so as to eject the medicament from the syringe 104 throughneedle 114.

In general, the valve 124 may be activated by the drug delivery device100 in any suitable manner. In the example embodiment of FIG. 1 , theneedle cover 116 and the sleeve 126 interact with one another in orderto activate the valve 124. To initiate the injection process, the userplaces the drug delivery device 100 on an injection site, such asinjection site 140 as shown in FIG. 3 . When the drug delivery device100 is pressed onto the injection site 140 in distal direction 132, theneedle cover 116 moves in a proximal direction 136 relative to the mainhousing 102. This retraction of the needle cover 116 exposes the needle114 and the needle 114 is consequently inserted into the injection site140.

In addition to exposing needle 114, this retraction of the needle cover116 also serves to activate the valve 124 of the pneumatic power pack120. In particular, the axial movement of the needle cover 116 in theproximal direction 136 causes axial movement of the sleeve 126 in theproximal direction 136. This axial movement of the sleeve 126 causes thesleeve 126 to interact with and activate the valve 124. The needleshield 116 may interact with sleeve 126 in any suitable manner in orderto move the sleeve 126 in order to activate the valve 124. In theexample shown in FIG. 2 , a coupling flange 138 is attached to thesleeve 126. Axial movement of the needle shield 116 in the proximaldirection 136 causes a proximal end 144 of the needle cover 116 toengage the coupling flange 138 and move the sleeve 126 in the proximaldirection 136 to activate the valve 124.

The sleeve 126 may interact with the valve 124 in any suitable manner inorder to activate the valve 124. In the example of FIG. 2 , valve 124includes a push portion 142 configured to open the valve 124. Inparticular, the valve 124 is configured to open when the push portion142 is moved a threshold amount in the proximal direction 136. Axialmovement of the sleeve 126 in the proximal direction 136 causes thesleeve 126 to contact the push portion 142 and then move the pushportion 142 the threshold amount in the proximal direction 136. Thismovement opens the valve 124 and releases the pressurized gas 123. Ingeneral, for such a push-activated valve, any suitable threshold amountof movement in the proximal direction 136 to activate the valve 124 ispossible. In an example, the threshold amount is between 0.5 and 5millimeters (mm). However, threshold amounts less than 0.5 mm andgreater than 5 mm are possible as well.

Although the example of FIG. 2 depicts a push-activated valve 124, inother example embodiments, the valve 124 may be activated in othersuitable ways. For instance, the valve 124 may include a twist portionthat is configured to open the valve 124 upon rotation. In such anexample, the device 100 is configured such that movement of the sleeve126 causes rotation of the twist portion to open the valve 124. Otherexamples are possible as well.

After activation of the valve 124, the pneumatic power pack 120 releasesthe pressurized gas 123 to automatically inject the dose of medicament112. The injection process is described in detail with reference toFIGS. 2 and 4-5 . As mentioned above, FIG. 2 depicts the device 100 inan initial state prior to injection. Further, FIG. 4 depicts thepneumatic power pack 120 and syringe 104 during dose delivery. Stillfurther, FIG. 5 depicts the pneumatic power pack 120 and syringe 104 atthe end of dose delivery.

In the initial state (see FIG. 2 ), a proximal end 146 of plunger 128 ispositioned in a proximal end 148 of the sleeve 126. When the valve 124is activated, the valve 124 releases the pressurized gas 123. Thepressurized gas 123 then flows into the sleeve 126 as indicated by arrow150 (see FIG. 4 ) and propels the plunger 128 in distal direction 132with respect to the sleeve 126 and syringe 104, so as to eject themedicament from the syringe 104 through the needle 114. Since sleeve 126is in gas-tight engagement with the pressurized gas source 122 and theplunger 128 is in sliding gas-tight engagement with the inner wall ofsleeve 126, the released pressurized gas 123 flowing into the sleeve 126creates a pressure sufficient to propel the plunger 128 in the distaldirection 132 with respect to the sleeve 126.

The pressurized gas 123 propels the plunger 128 in the distal direction132 until the stopper 118 reaches a distal end 152 of the syringe body110 (see FIG. 5 ). When the stopper 118 reaches the distal end 152 ofthe syringe body 110, the proximal end 146 of plunger 128 is positionedin a distal end 154 of sleeve 126.

During the dose delivery, the sleeve 126, syringe 104, and gas source122 may be axially fixed with respect to main housing 102. As a resultof these components being axially fixed during dose delivery, all orsubstantially all of the pressure from the released pressurized gas 123will beneficially go towards propelling the plunger 128 in the distaldirection 132.

In an example embodiment, the plunger 128 includes an inner chamberconfigured to receive the pressurized gas 123. FIG. 6 illustrates aperspective cross-sectional view of plunger 128, which includes innerchamber 170. During dispense, the pressurized gas 123 flowing intosleeve 126 will also flow into the inner chamber 170 of the plunger 128.Beneficially, the plunger 128 including an inner chamber 170 may help toreduce the mass of the plunger 128, and this may consequently reduce theforce required to propel the plunger 128 forward during dose delivery.

Although plunger 128 is depicted as having an open inner chamber 170 forreceiving pressurized gas 123, in other example embodiments, the innerchamber is closed such that pressurized gas 123 does not flow into theinner chamber 170. Such a closed inner chamber 170 may help to reducethe mass of the plunger 128, and this may consequently reduce the forcerequired to propel the plunger 128 forward during dose delivery. In yetother example embodiments, the plunger 128 does not include an innerchamber.

As mentioned above, sleeve 126 is in gas-tight engagement withpressurized gas source 122 and plunger 128 is in sliding gas-tightengagement with the inner wall 130 of sleeve 126. The gas-tightengagement between the sleeve 126 and gas source 122 may be provided inany suitable manner. For instance, the engagement between the sleeve 126and gas source 122 may include at least one washer or O-ring to providethe gas-tight engagement. Similarly, the sliding gas-tight engagementmay be provided in any suitable manner. For instance, at least onewasher or O-ring may be attached to the plunger 128 to provide thesliding gas-tight engagement with the inner wall 130. As seen in FIG. 4, plunger 128 includes a first washer 172 and a second washer 174attached at the proximal end 146 of the plunger 128. The plunger 128 mayinclude one or more ribs, such as ribs 178 and 180 (see FIG. 6 ), tohold the washers 172, 174 on the plunger 128. The washers 172, 174placed around the plunger 128 ensure that the space between the plunger128 and pressurized gas source 122 is substantially air-tight so thatany gas leakage that would reduce the thrusting force is minimized orprevented. Other methods for providing the gas-tight engagement betweenthe sleeve 126 and gas source 122 and for providing the slidable,gas-tight engagement with inner wall 130 are possible as well.

After injection is complete, the device 100 is removed from theinjection site 140 and the needle cover 116 will extend outward and lockinto place. This extension and locking may limit or prevent needle stickinjuries. The needle cover 116 may extend outward and lock into place inany suitable manner. In an example embodiment, when the drug deliverydevice 100 is removed from the injection site 140, the needle cover 116automatically extends outward in the distal direction 132 under a forcesuch as a spring force. As seen in FIG. 2 , drug delivery device 100includes spring 182 positioned between syringe 104 and needle cover 116.This spring 182 provides the force to automatically extend the needlecover 116 in the distal direction 132 after the user removes the drugdelivery device 100 from the injection site 140. Other ways of lockingthe needle cover 116 in an extended position are possible as well.

In an example embodiment, during dose delivery, the user can hear and/orfeel an audible and/or tactile feedback (e.g., clicking) throughout thedose delivery. For instance, the device 100 may include a clicker thanproduces a clicking sound when the plunger 128 is being propelledforward in the distal direction 132. The end of injection may beindicated by the audible/tactile clicking having stopped. Additionallyor alternatively, the stopper 118 and plunger 128 may be visible in themain body window 184 (see FIG. 3 ) when injection is complete. In suchan example, the end of delivery may be indicated by the stopper 118 andplunger 128 having stopped moving. Other indications of dose deliverybeing complete are possible as well.

Pressurized gas source 122 may be any source of pressurized gas suitableto propel the plunger 128 forward to eject the medicament 112. In anexample embodiment, the pressurized gas is CO₂, Argon, or Nitrogen.Other example pressurized gases are possible as well. Further, in anexample embodiment, the pressurized gas source 122 contains a gaspressurized to a pressure of between 50-3000 PSI. However, in otherexamples, the pressure may be less than 600 PSI or more than 3000 PSI.For instance, in another example, the pressure is between 500-600 PSI.In yet another example, the pressure is between 3000-3500 PSI. Otherexample pressures are possible as well.

Additionally, even though a syringe 104 is described in this exampleembodiment of FIG. 1 , any suitable type of medicament container may beused in the disclosed drug delivery device 100, such as a syringe, anampoule, a cartridge, an enclosure, etc. Further, the medicament may beany suitable substance used for medical treatment. In an exampleembodiment, the medicament is epinephrine (commonly known asadrenaline).

In an example embodiment, the disclosed pneumatic power pack may beconfigured to propel the plunger with a constant or substantiallyconstant force. An example drug delivery device having a pneumatic powerpack configured to propel the plunger with a constant or substantiallyconstant force is described with reference to FIGS. 7-10 .

FIG. 7 depicts a drug delivery device 200. The drug delivery device 200operates in a similar fashion as drug delivery devices 100; however,rather than including power pack 120, drug delivery device 200 includespower pack 202 (see FIG. 8 ). Other elements of drug delivery device 200may be the same or substantially similar to the other elements drugdelivery device 100, and thus drug delivery device 200 is not describedin as great of detail. It should be explicitly noted, however, that anypossibilities and permutations described above with respect to drugdelivery device 100 may equally apply to drug delivery device 200, andvice versa. Further, throughout the description of FIGS. 7-10 , elementsin drug delivery device 200 that are the same as or substantiallysimilar to elements in drug delivery device 100 are described with likereference numerals.

FIG. 8 depicts a cross-sectional view of power pack 202 of drug deliverydevice 200. Power pack 202 is positioned in second housing portion 108.Further, power pack 202 includes pressurized gas source 204 storingpressurized gas 206, valve 208, sleeve 210, and plunger 212 having innerchamber 214. Sleeve 210 is in gas-tight engagement with pressurized gassource 204 and plunger 212 is in sliding gas-tight engagement with aninner wall 211 of sleeve 210. In order to propel the plunger 212 with aconstant or substantially constant force, valve 208 is configured torelease the pressurized gas 206 at a substantially constant rate, andplunger 212 is configured to release pressure when the pressurized gas206 in the inner chamber 214 reaches a threshold pressure level.

With reference to FIG. 8 , valve 208 includes a flow control orifice216. Valve 208 also includes a gasket 218 configured to open and closethe flow control orifice 216. Flow control orifice 216 includes anopening 220 and an exit 222 and is sized to release pressurized gas 206at a substantially constant rate regardless of the pressure at theopening 220 and the pressure at exit 222. An example size of the flowcontrol orifice 216 may be on the order of 5 to about 250 Microns.

The flow control orifice 216 may release the pressurized gas at anysuitable substantially constant rate. As mentioned herein, by the term“substantially” it is meant that the recited characteristic, parameter,or value need not be achieved exactly, but that deviations orvariations, including for example, tolerances, measurement error,measurement accuracy limitations and other factors known to skill in theart, may occur in amounts that do not preclude the effect thecharacteristic was intended to provide.

In an example embodiment, the substantially constant rate at which theflow control orifice 216 releases the pressurized gas is anysubstantially constant rate. Further, as used herein, a substantiallyconstant rate of X means any rate in the range of X+/−0.05*(X).

Plunger 212 includes a pressure release valve 224 that is configured torelease pressure when the pressurized gas in the inner chamber 214reaches a threshold pressure level. The pressure release valve 224includes one or more release holes (such as release hole 226), gasket228, and spring 230. Gasket 228 and spring 230 are disposed in a distalend of inner chamber 214. When the pressure level in the inner chamber214 is below the threshold pressure level, the gasket 228 is positionedat a location proximal to a location of the release hole 226, so as toprevent the pressurized gas 206 from reaching the release hole 226. FIG.8 illustrates the gasket 228 positioned at a location proximal to alocation of the release hole 226. On the other hand, when the pressurelevel in the inner chamber 214 is above the threshold level, thepressurized gas 206 urges the gasket 228 against the spring 230 in adistal direction 132 until the gasket 228 moves distally beyond at leasta part of the release hole 226, so as to allow the pressurized gas 206to exit the release hole 226. FIG. 10 depicts the gasket 228 positionedat a location distal of the release hole 226.

In general, the threshold pressure level may be selected based on adesired force at which the plunger 212 is to be propelled. In an exampleembodiment, the threshold pressure level is a pressure level between 25PSI and 400 PSI.

In the example shown in FIG. 8 , pneumatic power pack 202 includes acontainer 230 for holding the pressurized gas source 204. The container230 includes a needle 232 that punctures the pressurized gas source 204during assembly of the power pack 202. In this example embodiment, thevalve 208 for the pressurized gas source 204 is provided by flow controlorifice 216 in container 230 and gasket 218. However, in otherembodiments, the pressurized gas source 204 may be replaced by a gassource that already has a release valve, such as valve 124.

During operation of the drug delivery device 200, valve 208 may beactivated in any suitable manner. In the example of FIG. 8 , the valve208 is activated by rotation of the gasket 218 to uncover the flowcontrol orifice 216. Similar to drug delivery device 100, movement ofthe needle cover 116 may act on the sleeve 210 to activate the valve208. For instance, axial movement of needle cover 116 acts on sleeve 210in order to rotate the gasket 218 in a clockwise direction 238 (see FIG.9 ) to uncover the flow control orifice 216. In one arrangement, thesleeve 210 and an inner housing portion enclosing the gasket 218 arecoupled during assembly. The needle cover 116 may act on either thesleeve 210 or the inner housing portion, depending on the designs, andthe gasket 218 will be rotated by the inner housing portion to open andactive the valve 208. In others words, the needle cover 116 can acteither the sleeve 210 or the inner housing portion to active the valve208.

When the valve 208 is activated by the rotation of gasket 218 to uncoverflow control orifice 216, the pressurized gas 206 moves through flowcontrol orifice 216 at a substantially constant flow rate as shown byarrow 240 (see FIG. 10 ). The pressurized gas 206 then moves into sleeve210 and inner chamber 214 as shown by arrow 242. Since the plunger 212is in sliding gas-tight engagement with the inner wall 211 of the sleeve210, the flow of gas shown by arrow 242 will increase the pressure inthe sleeve 210 and inner chamber 214 to propel the plunger 212 forwardin distal direction 132 so as to eject medicament 112. The pressurizedgas 206 propels the plunger 212 in the distal direction 132 with thesubstantially constant force until the stopper 118 reaches the distalend 152 of the syringe body 110. When the plunger 212 reaches this finalpoint, any remaining pressurized gas 206 will be released through thepressure release valve 224 until the pressurized gas source 204 is emptyor substantially empty.

During the propelling of the plunger 212 in the distal direction 132, ifthe pressure in the inner chamber 214 exceeds the threshold level, thepressurized gas 206 will get released through pressure release valve 224(as shown by arrow 244). This pressure release through pressure releasevalve 224 allows for effectively keeping the pressure in the innerchamber 214 at a substantially constant value. As a result of thepressure being regulated in this manner, the pneumatic power pack 202 isable to push the plunger 212 in the distal direction 132 with asubstantially constant force produced by the pressure in the sleeve 210and inner chamber 214.

The pneumatic power pack 202 may propel the plunger 212 forward with anysuitable substantially constant force. As mentioned herein, by the term“substantially” it is meant that the recited characteristic, parameter,or value need not be achieved exactly, but that deviations orvariations, including for example, tolerances, measurement error,measurement accuracy limitations and other factors known to skill in theart, may occur in amounts that do not preclude the effect thecharacteristic was intended to provide.

In an example embodiment, the substantially constant force at which theplunger 212 is propelled is any substantially constant force falling inthe range of forces between 10 N and 100 N+−15 N. Further, as usedherein, a substantially constant force of X Newtons means any force inthe range of 10 N and 100 N+−15 N.

Beneficially, the disclosed pneumatic power pack provides a costeffective means for propelling a plunger forward in an automaticinjection device. Further, embodiments of the disclosed pneumatic powerpack also provide a low-cost means for propelling the plunger forward ata substantially constant force. Therefore, the disclosed pneumatic powerpack may help to reduce the cost of manufacturing automatic injectiondevices.

In the examples shown in the Figures, the drug delivery devices 100 and200 are configured to inject a non-variable dose of medicament. However,in other embodiments, the drug delivery device could be configured toallow the user to select a variable single dose. For instance, in anexample embodiment, the user is able to select two different dosevalues, three different dose values, four different dose values, and soforth.

In the Figures, various engagement features for are shown for providingan engagement between one or more components of the drug deliverydevice. The engagement features may be any suitable connecting mechanismsuch as a snap lock, a snap fit, form fit, a bayonet, lure lock, threadsor combination of these designs. Other designs are possible as well.

It should be understood that the illustrated components are intended asan example only. In other example embodiments, fewer components,additional components, and/or alternative components are possible aswell. Further, it should be understood that the above described andshown embodiments of the present disclosure are to be regarded asnon-limiting examples and that they can be modified within the scope ofthe claims.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopebeing indicated by the following claims, along with the full scope ofequivalents to which such claims are entitled. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting.

We claim:
 1. A drug delivery device comprising: a main housing; asyringe arranged in the main housing, wherein the syringe comprises amedicament; a needle attached to the syringe; a needle cover axiallymovable with respect to the main housing; and a pneumatic power packarranged in the main housing, wherein the pneumatic power packcomprises: (i) a pressurized gas source storing pressurized gas; (ii) avalve for the pressurized gas source; (iii) a sleeve having an innerwall, wherein the sleeve is configured to receive pressurized gasreleased from the pressurized gas source; and (iv) a plunger axiallymovable with respect to both the sleeve and the syringe, wherein theplunger is in sliding gas-tight engagement with the inner wall of thesleeve, wherein, upon activation of the valve, the valve releases thepressurized gas and the released pressurized gas flows into the sleeveand propels the plunger in a distal direction with respect to the sleeveand the syringe, so as to eject the medicament from the syringe, andwherein axial movement of the needle cover in the proximal directioncauses axial movement of the sleeve in the proximal direction, andwherein the axial movement of the sleeve in the proximal directionactivates the valve to release the pressurized gas.
 2. The drug deliverydevice of claim 1, further comprising: a coupling flange attached to thesleeve, wherein axial movement of the needle cover in the proximaldirection causes the needle cover to engage the coupling flange and movethe sleeve in the proximal direction.
 3. The drug delivery device ofclaim 1, wherein the valve comprises a push portion configured to openthe valve, and wherein axial movement of the sleeve in the proximaldirection causes the sleeve to contact the push portion and open thevalve.
 4. The drug delivery device of claim 1, wherein the syringecomprises a stopper, and wherein movement of the plunger in the distaldirection with respect to the sleeve and the syringe causes the plungerto act on the stopper.
 5. The drug delivery device of claim 1, whereinthe plunger comprises an inner chamber configured to receive thereleased pressurized gas.
 6. The drug delivery device of claim 1,further comprising: at least one washer attached to the plunger, whereinthe at least one washer provides sliding gas-tight engagement with theinner wall of the sleeve.
 7. The drug delivery device of claim 1,wherein the valve comprises: a flow control orifice; and a gasketconfigured to open and close the flow control orifice.
 8. The drugdelivery device of claim 7, wherein axial movement of the needle coverin the proximal direction causes rotation of the gasket to open the flowcontrol orifice.
 9. The drug delivery device of claim 7, wherein thepneumatic power pack further comprises a container for holding thepressurized gas source, wherein the container comprises (i) the flowcontrol orifice and (ii) an additional needle configured to puncture thepressurized gas source.
 10. The drug delivery device of claim 1, whereinthe pneumatic power pack is configured to propel the plunger in thedistal direction with respect to the sleeve and the syringe at asubstantially constant force.
 11. The drug delivery device of claim 10,wherein the valve comprises a flow control orifice having an opening andan exit, wherein the flow control orifice is sized to release thepressurized gas at a substantially constant rate in response to apressure at the opening and a pressure at the exit.
 12. The drugdelivery device of claim 10, wherein the plunger comprises: an innerchamber configured to receive the released pressurized gas; and apressure release valve configured to release pressure when the receivedreleased pressurized gas in the inner chamber reaches a thresholdpressure level.
 13. The drug delivery device of claim 12, wherein thepressure release valve comprises: at least one release hole; and agasket and spring disposed in a distal end of the inner chamber, whereinthe gasket and spring are configured such that (i) below the thresholdpressure level, the gasket is positioned at a location proximal to alocation of the at least one release hole, so as to prevent the releasedpressurized gas from reaching the at least one release hole, and (ii)above the threshold pressure level, the released pressurized gas urgesthe gasket against the spring in a distal direction until the gasketmoves distally beyond at least part of the at least one release hole, soas to allow the received released pressurized gas to exit the at leastone release hole.
 14. The drug delivery device of claim 1, wherein thedrug delivery device is a single-use disposable injection device.
 15. Adrug delivery device comprising: a main housing; a medicament containerarranged in the main housing, wherein the medicament container comprisesa medicament; a needle cover axially movable with respect to the mainhousing; and a pneumatic power pack arranged in the main housing,wherein the pneumatic power pack comprises: (i) a pressurized gas sourcehaving a valve and storing pressurized gas; (ii) a sleeve having aninner wall, wherein the sleeve is axially moveable with respect to themain housing; and (iii) a plunger comprising an inner chamber, whereinthe plunger is axially movable with respect to both the sleeve and themedicament container, wherein the plunger is in sliding gas-tightengagement with the inner wall of the sleeve, and wherein the sleeve andthe inner chamber are configured to receive pressurized gas releasedfrom the pressurized gas source, wherein axial movement of the needlecover in a proximal direction causes axial movement of the sleeve in theproximal direction, wherein the axial movement of the sleeve in theproximal direction activates the valve to release the pressurized gas,and wherein the released pressurized gas flows into both the sleeve andthe inner chamber and propels the plunger in a distal direction withrespect to the sleeve and the medicament container, so as to eject themedicament from the medicament container.
 16. A drug delivery devicecomprising: a main housing; a medicament container arranged in the mainhousing, wherein the medicament container comprises a medicament; and apneumatic power pack arranged in the main housing, wherein the pneumaticpower pack comprises: (i) a pressurized gas source storing pressurizedgas; (ii) a valve for the pressurized gas source; (iii) a sleeve havingan inner wall; and (iv) a plunger comprising an inner chamber and apressure release valve configured to release pressure from the innerchamber when the pressure in the inner chamber reaches a thresholdpressure level, wherein the inner chamber of the plunger is axiallymovable with respect to both the sleeve and the medicament container,wherein the inner chamber of the plunger is in sliding gas-tightengagement with the inner wall of the sleeve, wherein the sleeve and theinner chamber are configured to receive pressurized gas released fromthe pressurized gas source, wherein the valve is configured to releasethe pressurized gas upon activation of the valve, and wherein thereleased pressurized gas is configured to flow into both the sleeve andthe inner chamber to propel the inner chamber of the plunger in a distaldirection with respect to the sleeve and the medicament container with asubstantially constant force, such that the plunger moves into themedicament container to eject the medicament from the medicamentcontainer.
 17. The drug delivery device of claim 16, wherein thepressure release valve comprises: at least one release hole; and agasket and spring disposed in a distal end of the inner chamber, whereinthe gasket and spring are configured such that (i) below the thresholdpressure level, the gasket is positioned at a location proximal to alocation of the at least one release hole, so as to prevent the releasedpressurized gas from reaching the at least one release hole, and (ii)above the threshold pressure level, the released pressurized gas urgesthe gasket against the spring in a distal direction until the gasketmoves distally beyond at least part of the at least one release hole, soas to allow the received released pressurized gas to exit the at leastone release hole.
 18. The drug delivery device of claim 17, wherein thevalve comprises a flow control orifice having an opening and an exit,wherein the flow control orifice is sized to release the pressurized gasat a substantially constant rate regardless of a pressure at the openingand a pressure at the exit.
 19. The drug delivery device of claim 1,wherein the needle cover directly contacts and engages the sleeve whenthe needle cover moves proximally from a first position to a secondposition.
 20. A drug delivery device comprising: a main housing having adistal end and a proximal end; a container of medicament axially fixedwithin the main housing and having a stopper slidably positioned withinthe container of medicament; a needle cover slidably positioned withinthe main housing and axially movable between a first position and asecond position, where when the needle cover is in the first position adistal portion of the needle cover extends out beyond the distal end ofthe main housing; a container of pressurized gas positioned at theproximal end of the main housing; a valve operatively associated withthe container of pressurized gas; a sleeve that is operatively engagedwith the container of pressurized gas such that the sleeve will be in agas tight engagement with the container of pressurized gas source whenthe needle cover is in the second position; and a plunger positionedwithin the sleeve and comprising a seal that forms a gas tightengagement with an inner wall of the sleeve such that pressurized gasreleased from the container of pressurized gas will cause the plunger tomove axially in a distal direction relative to the main housing and thesleeve when the needle cover is in the second position, wherein movementof the needle cover from the first position to the second position movesthe sleeve in a proximal direction relative to the main housing, wherethe proximal movement of the sleeve causes the valve to open releasingthe pressurized gas into the sleeve, and wherein axial movement of theplunger causes axial movement of the stopper relative to the mainhousing, sleeve and the container of medicament.
 21. The drug deliverydevice of claim 20, wherein the needle cover directly contacts andengages the sleeve when the needle cover moves from the first positionto the second position.
 22. The drug delivery device of claim 20,wherein the plunger further comprises an inner chamber, whereinpressurized gas released from the container of pressurized gas willenter both the sleeve and the inner chamber to cause the plunger to movedistally relative to the sleeve and the container of medicament.
 23. Thedrug delivery device of claim 20, wherein the valve further comprises aflow control orifice having an opening and an exit, wherein the flowcontrol orifice is sized to release the pressurized gas at asubstantially constant rate in response to a pressure at the opening anda pressure at the exit.